1. Field of the Invention
The present invention relates to a magnetic recording and reproducing apparatus for use in a video tape recorder (or VTR) or the like.
With respect to an azimuth adjustment of a magnetic head, a specified azimuth angle is prepared during manufacture of the magnetic head gap so as to be merely placed on the magnetic head, while, in the cutting of the magnetic head chip, it is very difficult to achieve accuracy in cutting angles in the order of several minutes. Furthermore, when the magnetic head base on which the magnetic head chip is mounted is deformed by mechanical vibrations or temperature variations, the attaching azimuth angle is also subjected to variations, and the accuracy at the initial stage can not be maintained. Additionally, there may arise such a problem that, if reproduction is effected by another VHS video tape recorder, with the azimuth angle of the magnetic head of a VHS video tape recorder remaining to be deviated, the output is undesirably lowered due to difference in the azimuth angles.
On the other hand, as shown in FIG. 5, there is a contact type azimuth angle adjusting method which is arranged to give strain to a magnetic head base 11 with a head chip 10 of a magnetic head including upper and lower cylinders 2 and 3, by pressing a setting screw 1 against the magnetic head base 11 as in the video tape recorder of M2 mainly utilized for broadcasting purpose. However, in the above conventional arrangement, there are many factors for generating vibrations such as the rotation of the cylinder, tape transportation, etc., while deviation in the azimuth angle due to variations with time by the heat generated from such driving system, or variations in temperature arising from change in working circumstances, etc. can not be avoided.
Currently, in order to minimize the influence from such factors, a screw loosening prevention agent (i.e. resin which solidifies in normal temperature) is used with respect to the setting screw, but its effect is not sufficient, and the height of the magnetic head is altered in the order of several microns, with a consequent variations in the azimuth angle. Accordingly, there has been required a non-contact type azimuth adjustment of magnetic heads for solving the problems as described above.
Meanwhile, as examples of processing by the heat of laser, there was disclosed in a magazine "Machine and tool" published by Kogyo Chosakai, July 1987 a report entitled "Laser forming" by Y. Namba, which describes a processing method for bending a stainless steel flat plate material into a loop shape after irradiation of laser. Furthermore, there has been another report in chapter 3 of "welding engineering" related to "welding stress and welding deformation" (published by Rikogakusha, 1979, ISBN4-8445-2108-X) by K. Sato, Y. Mukai, and M. Toyota.
2. Description of the Prior Art